Emptying of the Dounreay Fast Reactor east pond is almost complete.
This six metre deep concrete chamber has been drained of its 500m3 of water in preparation for removing the concrete and bitumen liner as the former reactor is pulled apart. The remaining sludge has been captured in a basket.
Previously the sludge had been removed via agitating and filtering the suspended solids. The project team then designed and implemented a process to capture the remaining mass in a basket and thus minimise the quantity of filters for grouting and storing in 200L waste drums. The processes for grouting the captured sludge are in the final review phase.
Completing the water and sludge removal in the west pond has proved more challenging due to the higher radiation from the pond walls, floor and sludge. Shielding installed on the pond walls has successfully reduced that dose, but the radiation levels have continued to increase as the water level has been lowered. The team believe the majority of the radiation is from the remaining sludge and so have been preparing to collect and transfer it to shielded baskets whilst leaving the water in place.
Project manager George Groat said: “Everyone has worked very hard to develop fresh approaches as the character and quantity of the sludge is being revealed. We’re looking forward to the day when the water level is low enough that the remaining sludge is visible as it is obviously much easier to deal with a problem that can been seen.”